There is a problem in electrical circuits in that, as electrical circuit current increases, so does the potential for electrical arcing when electrically loaded mechanical connections in relays and switches separate. Furthermore, where such connections or electrical contacts move slowly, arc damage can be severe, particularly as most known switching mechanisms on printed circuit boards involve horizontal sliding elements moving at hand operating speed. Conventional circuit board material is thin copper with, at best, a plated layer of silver or gold to minimise surface oxidation and improve electrical connection, and so any substantial erosion of the board material by arcing or surface heating will severely impact the performance of the switching function.
Most known multi-function switches utilise a single moving contact or contact pair sliding over or past multiple circuit board contact locations, and so any damage to the faces of such a moving contact set at one location can be transferred to other contact faces at other board locations thereby accelerating failure of the contact set.
Where reactive loads, such as large transformers or capacitators are being managed by such switches, the momentary high voltage or currents can substantially increase “make and break” arcing. This arcing, although it occurs for a very short duration, causes significant contact surface melting and damage to the primary connection faces which, when the contact faces have settled, increases contact voltage drop and generates increased contact heating when high current is present. Variable contact voltage drop causes variability of the heat generated at contact locations to the degree that the performance of plastic components in switches can be compromised, and so, where such plastic components are used to support pressure components, such as springs, this compromised performance will lead to the total failure of the switch in many cases.
Conventionally, to reduce voltage drop across contacts, higher contact pressure is used. For sliding contacts, this increased pressure also means increased drag which degrades switch operation “feel”. This then requires increased pressure on the detent mechanism which results, over time, in an even higher amount of effort needed to operate the switch as switching current rating increases.